arXiv subjects

J. Kuti

Publications and source records attributed to J. Kuti.

15 recordsLinked to original sources

arXiv2013

Report of the Snowmass 2013 Computing Frontier working group on Lattice Field Theory -- Lattice field theory for the energy and intensity frontiers: Scientific goals and computing needs

This is the report of the Computing Frontier working group on Lattice Field Theory prepared for the proceedings of the 2013 Community Summer Study ("Snowmass"). We present the future computing needs and plans of the U.S. lattice gauge theory community and argue that continued support of the U.S. (and worldwide) lattice-QCD effort is essential to fully capitalize on the enormous investment in the high-energy physics experimental program. We first summarize the dramatic progress of numerical lattice-QCD simulations in the past decade, with some emphasis on calculations carried out under the auspices of the U.S. Lattice-QCD Collaboration, and describe a broad program of lattice-QCD calculations that will be relevant for future experiments at the intensity and energy frontiers. We then present details of the computational hardware and software resources needed to undertake these calculations.

hep-lat↗

arXiv2004

QCD String formation and the Casimir Energy

Three distinct scales are identified in the excitation spectrum of the gluon field around a static quark-antiquark pair as the color source separation R is varied. The spectrum, with string-like excitations on the largest length scales of 2-3 fm, provides clues in its rich fine structure for developing an effective bosonic string description. New results are reported from the three-dimensional Z(2) and SU(2) gauge models, providing further insight into the mechanism of bosonic string formation. The precocious onset of string-like behavior in the Casimir energy of the static quark-antiquark ground state is observed below R=1 fm where most of the string eigenmodes do not exist and the few stable excitations above the ground state are displaced. We find no firm theoretical foundation for the widely held view of discovering string formation from high precision ground state properties below the 1 fm scale.

hep-lat↗

arXiv2003

Excitations of torelon

The excitations of gluonic flux tube in a periodic lattice are examined. Monte Carlo simulations from an anisotropic lattice are presented and the comparison with effective string models is discussed.

hep-lat↗

arXiv2003

How light can the Higgs be?

It is widely believed that, for a given Top mass, the Higgs mass has a lower bound: if m_Higgs is too small, the Higgs vacuum is unstable due to Top dynamics. From vacuum instability, the state-of-the-art calculation of the lower bound is close to the current experimental limit. Using non-perturbative simulations and large N calculations, we show that the vacuum is in fact never unstable. Instead, we investigate the existence of a new lower bound, based on the intrinsic cut-off of this trivial theory.

hep-lat↗

arXiv2001

The QCD String Spectrum and Conformal Field Theory

The low energy excitation spectrum of the critical Wilson surface is discussed between the roughening transition and the continuum limit of lattice QCD. The fine structure of the spectrum is interpreted within the framework of two-dimensional conformal field theory.

hep-lat↗

arXiv1999

Quark Confinement and Surface Critical Phenomena

Surface critical phenomena and the related onset of Goldstone modes probe the fundamental properties of the confining flux in Quantum Chromodynamics. New ideas on surface roughening and their implications for lattice studies of quark confinement are presented. Problems with the oversimplified string description of the Wilson flux sheet are discussed.

hep-lat↗

arXiv1999

The Heavy Hybrid Spectrum from NRQCD and the Born-Oppenheimer Approximation

The spectrum of heavy-quark hybrids is studied in the leading Born-Oppenheimer (LBO) approximation and using leading-order NRQCD simulations with an improved gluon action on anisotropic lattices. The masses of four hybrid states are obtained from our simulations for lattice spacings 0.1 fm and 0.2 fm and are compared to the LBO predictions obtained using previously-determined glue-excited static potentials. The consistency of results from the two approaches reveals a compelling physical picture for heavy-quark hybrid states.

hep-lat↗

arXiv1999

Ab Initio Study of Hybrid b-bar-gb Mesons

Hybrid b-bar-gb molecules in which the heavy b-bar-b pair is bound together by the excited gluon field g are studied using the Born-Oppenheimer expansion and numerical simulations. The consistency of results from the two approaches reveals a simple and compelling physical picture for heavy hybrid states.

hep-ph↗

arXiv1998

Exotica and the Confining Flux

Recent developments in Quantum Chromodynamics (QCD) are reviewed on three major topics where nonperturbative gluon excitations of the QCD vacuum and the physical properties of the confining flux play a central role: (1) New lattice results on the spectrum and wave functions of heavy quark-antiquark molecules, known as heavy hybrids, will be discussed. (2) Recent advances on the glueball spectrum in lattice QCD will be presented with some theoretical observations. (3) Progress in our understanding of the nonperturbative internal structure of the confining flux and its excitation spectrum will be reported.

hep-lat↗

arXiv1998

Where is the string limit in QCD?

The energies of glue in the presence of a static quark-antiquark pair are calculated for separations r ranging from 0.1 fm to 4 fm and for various quark-antiquark orientations on the lattice. Our simulations use an improved gauge-field action on anisotropic space-time lattices. Discretization errors and finite volume effects are studied. We find that the spectrum does not exhibit the expected onset of the universal pi/r Goldstone excitations of the effective QCD string, even for r as large as 4 fm. Our results cast serious doubts on the validity of treating glue in terms of a fluctuating string for r below 2 fm. Retardation effects in the Upsilon system are also studied by comparing level splittings from the Born-Oppenheimer approximation with those directly obtained in simulations.

hep-lat↗

arXiv1998

Gluon excitations of the static-quark potential

The spectrum of gluon excitations in the presence of a static quark-antiquark pair is presented. Our results are obtained from computer simulations of gluons on anisotropic space-time lattices using an improved gauge-field action. Measurements for quark-antiquark separations r ranging from 0.1 fm to 4 fm and for various orientations on the lattice are made. Discretization errors and finite volume effects are taken into account. Surprisingly, the spectrum does not exhibit the expected onset of the universal pi/r Goldstone excitations of the effective QCD string, even for r as large as 4 fm.

hep-lat↗

arXiv1997

A study of hybrid quarkonium using lattice QCD

The hybrid quarkonium states are studied using the Born-Oppenheimer expansion. The first step in this expansion is the determination of the energy levels of the gluons in the presence of a static quark-antiquark pair as a function of the quark-antiquark separation. The spectrum of such gluonic excitations is determined from first principles using lattice QCD.

hep-ph↗

arXiv1997

Gluon excitations of the static quark potential and the hybrid quarkonium spectrum

A comprehensive determination of the rich, low-lying spectrum of gluonic excitations in the presence of a static quark-antiquark pair is presented. Our results are obtained from several simulations on anisotropic lattices using an improved action and a large set of gluonic operators. The hybrid quarkonium states are studied in the quenched approximation using the Born-Oppenheimer expansion and nonrelativistic lattice QCD.

hep-lat↗

arXiv1997

Bag Picture of the Excited QCD Vacuum with Static Q-Qbar Source

The gluon excitations of the QCD vacuum are investigated in the presence of a static quark-antiquark source. It is shown that the ground state potential and the excitation spectrum of dynamical gluon degrees of freedom, as determined in our lattice simulations, agree remarkably well with model predictions based on the diaelectric properties of the confining vacuum described as a dual superconductor. The strong chromoelectric field of the static Q-Qbar source creates a bubble (bag) in the condensed phase where weakly interacting gluon modes can be excited. Some features and predictions of the bag model are presented and the chromoelectric vortex limit at large quark-antiquark separation (string formation) is briefly discussed.

hep-lat↗

arXiv1994

Strongly Interacting Higgs Sector without Technicolor

Simulation results are presented on Higgs mass calculations in the spontaneously broken phase of the Higgs sector in the minimal Standard Model with a higher derivative regulator. A heavy Higgs particle is found in the TeV mass range in the presence of a complex conjugate ghost pair at higher energies. The ghost pair evades easy experimental detection. As a finite and unitary theory in the continuum, this model serves as an explicit and simple example of a strongly interacting Higgs sector without technicolor.

hep-lat↗